Cytotoxic iridoid glycosides from the aerial parts of Paederia yunnanensis

Three previously undescribed iridoid glycosides, 6α-O-trans-sinapoyl-paederosidic acid ethyl ester (1), 6'-O-trans-feruloyl-paederosidic acid methyl ester (2), and 10-O-trans-p-coumaroyl-(4S,6R)-3,4-dihydro-3β-ethoxypaederoside (3), were isolated from the 90% EtOH extract of the aerial parts of Paederia yunnanensis. The structures of the new compounds were elucidated by spectral methods such as 1D and 2D (1H-1H COSY, HMQC, and HMBC) NMR spectrometry, HR-ESI-MS, as well as ECD data. The isolated compounds were tested in vitro for cytotoxic activity against five tumor cell lines. These results revealed that 3 exhibited some cytotoxicities against all the tested tumor cell lines with IC50 value less than 20.0 μM and provided a scientific basis for further processing and utilization of P. yunnanensis.